Messages in this thread Patch in this message | | | From | Jeff Layton <> | Subject | [PATCH v2 1/4] fs: have flush_delayed_fput flush the workqueue job | Date | Thu, 17 Sep 2015 08:39:44 -0400 |
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I think there's a potential race in flush_delayed_fput. A kthread does an fput() and that file gets added to the list and the delayed work is scheduled. More than 1 jiffy passes, and the workqueue thread picks up the work and starts running it. Then the kthread calls flush_delayed_work. It sees that the list is empty and returns immediately, even though the __fput for its file may not have run yet.
Close this by making flush_delayed_fput use flush_delayed_work instead, which should immediately schedule the work to run if it's not already, and block until the workqueue job completes.
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> --- fs/file_table.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/file_table.c b/fs/file_table.c index ad17e05ebf95..52cc6803c07a 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -244,6 +244,8 @@ static void ____fput(struct callback_head *work) __fput(container_of(work, struct file, f_u.fu_rcuhead)); } +static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput); + /* * If kernel thread really needs to have the final fput() it has done * to complete, call this. The only user right now is the boot - we @@ -256,11 +258,9 @@ static void ____fput(struct callback_head *work) */ void flush_delayed_fput(void) { - delayed_fput(NULL); + flush_delayed_work(&delayed_fput_work); } -static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput); - void fput(struct file *file) { if (atomic_long_dec_and_test(&file->f_count)) { -- 2.4.3
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